Building an ADU in Ventura

What you can build in Ventura

The city's rules are in Chapter 24.430 of the San Buenaventura Municipal Code, rewritten by Ordinance 2024-12. The council adopted it on January 14, 2025 to match 2024 state law changes. It took effect 30 days later outside the Coastal Zone; inside the Coastal Zone the changes take effect only after Coastal Commission approval.

An ADU can go on a lot in a residential or mixed-use zone. A junior ADU only on a lot zoned for single-family homes.

Building permit only. These ADUs need nothing more than a building permit if they meet the general rules below:

• On a single-family lot: one ADU converted from space in the house or an existing accessory building (plus up to 150 sq ft for entry), and one junior ADU.
• Also on a single-family lot: one new detached ADU of up to 800 sq ft, with 4-foot side and rear setbacks and within the height limit.
• On a multifamily lot: conversions of non-living space (storage rooms, garages and the like), at least one and up to 25% of the existing units.
• On a multifamily lot: up to two detached ADUs with a proposed building, or up to eight with an existing building (no more than the number of existing units).

Other ADUs (for example, a detached ADU over 800 sq ft or an attached addition) must meet the extra size, coverage, setback and design standards described below.

The city's ADU web page FAQ still says single-family homes can have one ADU, plus a junior ADU if owner-occupied, and that multifamily lots can add up to two detached ADUs. That text predates the 2025 ordinance. HCD reads state law to require, on a single-family lot, one converted ADU, one junior ADU and one new detached ADU together. Confirm your combination with the city. Statewide rules are on our California page. [1][2][3][4]

Size, height and setbacks

Height (all ADUs). A detached ADU can be 18 feet tall, or up to 20 feet to match the main home's roof pitch. An attached ADU can be 25 feet and two stories. Height is measured from the average curb grade at the front lot line, with special rules for sloping lots, through lots and the R-1-B and R-2-B zones.

Extra standards for ADUs outside the building-permit-only categories:

• Size: 850 sq ft for a studio or one bedroom, 1,200 sq ft for two or more bedrooms. An attached ADU is also capped at 50% of the existing home's floor area. Other rules can't shrink an ADU below 800 sq ft.
• Site coverage: total lot coverage up to 35% in R-1, 40% in R-1-B, and 60% in R-2, R-2-B, R-3 and other zones.
• Setbacks: 4 feet side and rear; front setback by zone (20 feet in R-1-B, R-2-B and most other zones). No setback is needed if you rebuild in the same place and size as an existing structure.
• One story only for detached units.
• Design: exterior materials and colors must match the house, the roof slope must match its main slope, lighting must point down, and windows or doors can't have a direct line of sight into a neighbor's property unless screened.

Historic properties. An ADU on or within 600 feet of a property listed in the California Register of Historical Resources must sit fully behind the main home, not be visible from the street, match its materials, colors and roof pitch, and be no taller than the existing structure.

An ADU that doesn't meet these objective standards may still be approved with a conditional use permit. [1]

Parking, fire zones and the coastal zone

Parking. No parking is required for ADUs or junior ADUs, and garage, carport or driveway spaces removed for an ADU don't have to be replaced. The exception is the ADU Mandatory Parking Area, mapped in parts of Downtown and the Pierpont area. There, the ADU or junior ADU needs one space, and parking displaced by the ADU must be replaced. The space can be tandem on a driveway, covered or uncovered, and must be 9 by 20 feet. State law bars parking requirements for ADUs within a half-mile walk of public transit, among other exemptions, and for the state-law ADU categories. HCD's handbook also says a city can't require you to replace parking removed to build an ADU. If your lot is in the mapped area, ask the city whether an exemption applies.

Very high fire hazard zones. The city does not permit ADUs in designated very high fire hazard severity zones, but junior ADUs are allowed. The building-permit-only categories above (state-law ADUs) are exempt from this ban, as are applications submitted on or before May 13, 2022. HCD's ADU Handbook says fire hazard maps are "not intended to restrict housing development" and that safety-based restrictions should be backed by findings.

Coastal Zone. In the Coastal Zone every ADU and junior ADU needs a coastal exemption, coastal exclusion or coastal development permit, but no public hearing. ADUs there must avoid harm to wetlands, streams, habitat, views, public access and bluffs. They aren't allowed in existing buildings that are nonconforming to coastal rules. [1][2][4]

Fees and utilities

Impact fees. The city code charges no impact fee for an ADU under 750 sq ft. Above that, impact fees are charged in proportion to the main home: the ADU's floor area divided by the home's floor area, times the normal fee for a new home. HCD's handbook says an ADU with 750 sq ft or less of interior livable space is exempt, so if yours is exactly 750 sq ft, confirm with the city.

Utility connections. A converted ADU on a single-family lot (in the building-permit-only category) needs no new or separate utility connection and pays no connection fee or capacity charge. Most other ADUs need a new, separate connection for city-provided utilities, with a fee proportional to the ADU's size or plumbing fixtures. If you build the ADU together with a new house, normal new-home connection fees apply. Utilities the city doesn't provide follow their own provider's rules.

Permit fees. The city may charge a fee set by council resolution to cover processing ADU permits. Using the city's free standardized plans reduces review fees.

Other requirements. Sprinklers are required in an ADU only if the main home needs them, and an ADU can't trigger sprinklers in the existing home. If the ADU uses a septic system, include a percolation test from the last five years. The County of Ventura's ADU calculator can help you budget. See our ADU cost guide. [1][2][4]

Free standardized ADU plans

The city offers complete, free construction plans for detached ADUs that the Building and Safety Division has already reviewed. Using them saves on the city's review fees and review time, and the city says they generally reduce the need to hire an architect if you build exactly as approved. Three layouts are on the city's ADU page:

• 1 bedroom, 700 sq ft
• 2 bedrooms, 900 sq ft
• 3 bedrooms, 1,188 sq ft

You can't move or resize features like doors, vents or plumbing connections, but you can change paint, siding, trim and light fixtures (some changes need Building and Safety approval). Plans over 800 sq ft fall outside the building-permit-only category, so check the size, setback and one-story rules above for your lot. See our prefab ADU guide. [1][2]

How long it takes

The city must approve or deny a complete ADU or junior ADU application within 60 days, or it is deemed approved. The clock pauses if you ask for a delay, and the city can wait to act on an ADU filed with a new house. A denial must list every deficiency and how to fix it. A demolition permit for a detached garage being replaced by an ADU is reviewed and issued along with the ADU. Under state law, the city must also tell you within 15 business days whether your application is complete.

Before the certificate of occupancy, you must record a city deed restriction: no separate sale, and the unit stays at its approved size. It can be removed later if you eliminate the ADU. See our ADU permit guide. [1][4]

Garage conversions and junior ADUs

Garage conversions. On a single-family lot, converting an existing garage or other accessory building is a building-permit-only ADU. It can add up to 150 sq ft for entry, needs its own outside access, and needs side and rear setbacks that meet fire and safety codes. There is no size limit for converting an existing accessory structure. You don't have to replace the garage parking (except in the ADU Mandatory Parking Area). See our garage conversion guide.

Junior ADUs. A junior ADU is up to 500 sq ft, contained entirely within an existing or proposed single-family home (an attached garage counts). It needs its own outside entrance and at least an efficiency kitchen. If it has no bathroom of its own, it must have an inside door to the main living area. No parking is required, except in the ADU Mandatory Parking Area.

Owner occupancy. Ventura's 2025 ordinance says all junior ADUs require the owner to live on site, in the house or the junior ADU. Since January 1, 2026, state law requires owner occupancy only when the junior ADU shares a bathroom with the house. Ask the city which rule it applies. See our junior ADU guide. [1][2][4]

Renting it out and unpermitted units

ADUs created on or after January 1, 2020 have no owner-occupancy requirement. You can rent out an ADU or junior ADU, but not for less than 30 days, no matter when the unit was built. An ADU can't be sold separately from the lot and home, except under the state's narrow nonprofit exception (Government Code 66341).

Unpermitted units. The city can't deny a permit to legalize an ADU or junior ADU built before January 1, 2020 just because it breaks building standards or ADU rules. It can deny only if a fix is needed to meet the state's substandard building standards. The city also won't deny a new ADU because of unrelated nonconforming conditions on the lot that don't threaten health and safety. [1]

Permit steps in Ventura

1. Check your zone and overlays

   Confirm your zoning, and whether your lot is in the Coastal Zone, a very high fire hazard severity zone, the ADU Mandatory Parking Area, or near a California Register historic property. [1]

2. Choose your plans

   Use the city's free standardized plans from the ADU page, or have custom plans drawn to Chapter 24.430. [1][2]

3. Get coastal clearance if needed

   In the Coastal Zone, get a coastal exemption, exclusion or coastal development permit (no public hearing). [1]

4. Apply for a building permit

   Ask the city how to submit your building permit application: call 805-654-7869 or email permits@cityofventura.ca.gov. [2]

5. Review and decision

   The city must approve or deny a complete application within 60 days; a garage demolition permit is issued with the ADU permit. [1]

6. Record the deed restriction and finish

   Record the city's deed restriction with the County Recorder before the certificate of occupancy is issued. [1]

Pre-approved and sample plans

• City of Ventura Standardized ADU Plans

  Free, pre-reviewed construction plans for detached ADUs in 700, 900 and 1,188 sq ft layouts, with reduced review fees and time. [2]

Who to call

• City of Ventura Community Development

  ADU questions and building permits; permits@cityofventura.ca.gov. City Hall public counter: walk-in Monday-Thursday 8 a.m.-1 p.m., by appointment 1-3 p.m., closed Fridays

  805-654-7869

  501 Poli Street, Ventura, CA 93001

  [2]

Questions people ask